Light module with protective element to prevent the passage of electrostatic discharges between the outer and inner parts of the light module

Description

TECHNICAL FIELD TO WHICH THE INVENTION RELATES

[0001] The present invention relates to a lighting device for a motor vehicle, comprising electronic components sensitive to electrostatic discharges, for example, light-emitting diodes. More specifically, the invention relates to a lighting module comprising a protective element to prevent the passage of electrostatic discharges between the outside and the inside of the lighting module. TECHNOLOGICAL BACKGROUND

[0002] In the automotive sector, lighting systems increasingly rely on electronic components to create compact, high-power light sources, such as light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), or laser diodes. Positioning these lighting devices along precise contours allows for the creation of unique optical signatures. However, these electronic components are particularly susceptible to electrostatic discharge. Light sources are typically surrounded by, or at least located near, reflectors, which concentrate the emitted light towards the front of the lighting system. These reflectors, formed by a metallic surface, have the drawback of allowing electrostatic discharges to pass through to the light sources.To prevent this, it is known to isolate reflectors and light sources from the external environment by sealing them in an electrically non-conductive casing.

[0003] The various components of the housing are held in place by fixing screws, the heads of which are flush with the outside of the housing. Metal fixing screws are preferred due to their mechanical resistance to shocks and temperature variations. However, the use of metal fixing screws has the disadvantage of creating conductive pathways between the outside and inside of the housing, allowing electrostatic discharges to pass to the light sources via the reflectors. DE 10 2016 213778 A1 discloses a prior art light module for a motor vehicle.

[0004] The invention aims to remedy this, by proposing a light module for motor vehicles, comprising a protective element to prevent the passage of electrostatic discharges between the outside and inside of the light module via metal fixing screws. SUBJECT OF THE INVENTION

[0005] In order to remedy the aforementioned drawback of the prior art, the present invention proposes a light module for motor vehicles comprising a housing in which are present an electrically conductive support and at least one semiconductor light source, in contact or near the support, the light module also includes at least one electrically conductive fastening means comprising a first part present outside the housing and a second part passing near or through the support.

[0006] The invention is remarkable in that the light module includes a protective element against electrostatic discharges, interposed between the second part of the fixing element and the support, and in that the protective element extends along the second part of the fixing means so as to prevent the passage of an electrostatic discharge between the fixing means and the support.

[0007] The invention therefore proposes interposing a protective element between the fastening means and the support, the protective element being configured to prevent the passage of electrostatic discharges. Thus, electrically conductive fastening means can be used for their mechanical resistance to shocks and temperatures, while limiting the risk of damage to light sources by electrostatic discharges passing through said fastening means.

[0008] According to one embodiment of the invention, the protective element is formed from a plastic material of the type acrylonitrile butadiene styrene (ABS), polycarbonate (PC) or a mixture of the two.

[0009] According to another embodiment of the invention, the thickness of the protective element is between 1 mm and 10 mm or between 2 mm and 8 mm, preferably between 2 mm and 3 mm. In other words, the thickness of the protective element is chosen to prevent the passage of an electrostatic discharge through it. The thickness of the protective element is also chosen to minimize its size within the housing. The term "thickness" refers to the smallest distance between opposite faces of a wall of the protective element.

[0010] According to another embodiment of the invention, the protective element extends along the second part of the fastening means, such that the shortest path around the protective element, between the fastening means and the support, is equal to or greater than 20 mm. According to another embodiment, the protective element extends beyond the second part of the fastening means.

[0011] According to another embodiment of the invention, the protective element is a wall interposed between the electrically conductive support and the second part of the fastening means.

[0012] According to another embodiment of the invention, the protective element is a sheath partially or completely surrounding the second part of the fastening means. In another embodiment, the length of the sheath varies around the fastening means. The term "length" refers to a dimension of the sheath along a direction substantially parallel to the longitudinal axis of the fastening means. In a preferred embodiment, a side wall of the protective element is shorter when said side wall is opposite a non-conductive element. This embodiment aims to limit the size of the protective element in areas of the housing that do not contain an electrically conductive support.

[0013] According to the invention, the protective element extends from an inner face of the housing. This embodiment aims to provide improved electrical insulation along the entire length of the second part of the fastening means. In a preferred embodiment, the protective element is integral with the inner face of the housing. In another preferred embodiment, the protective element forms a projection from an inner face of the housing.

[0014] According to another embodiment of the invention, the fastening means is reversible. According to a preferred embodiment, the fastening means is a fixing screw comprising a head flush with the outside of the housing and a threaded shank extending inside the housing.

[0015] According to another embodiment of the invention, the support is an electronic card comprising conductive tracks connected to at least one light source or an optical reflector comprising a metallic layer.

[0016] According to another embodiment of the invention, the semiconductor light source is a light-emitting diode.

[0017] Of course, the different characteristics, variants and forms of realization mentioned above can be associated with each other in various combinations, insofar as they are not incompatible or exclusive of each other.

[0018] The invention also relates to a signaling and / or lighting device for a motor vehicle, comprising one of the light modules described above.

[0019] The invention also relates to a motor vehicle comprising a signaling and / or lighting device described above. DESCRIPTION OF THE FIGURES

[0020] The description that follows with regard to the figure 1 The attached diagram, given as a non-limiting example, will allow for a better understanding of what the invention consists of and how it can be implemented. figure 1 represents a cross-section of a light module according to the invention comprising a protective element against electrostatic discharges from outside the light module. DETAILED DESCRIPTION OF A PROJECT EXAMPLE

[0021] As a reminder, the invention proposes a light module for motor vehicles, including a protective element to prevent the passage of electrostatic discharges between the outside and inside of the light module.

[0022] There figure 1presents an embodiment of a light module 2 according to the invention. The light module comprises a housing 4 consisting of a rear part 6 forming a housing 8, closed by a front part 10 of the housing.

[0023] Housing 8 accommodates at least one semiconductor light source, in this case a light-emitting diode 12, arranged on an electronic board 14. The electronic board has conductive tracks 16 on its surface allowing a control unit not shown on the figure 1to control the operation of the light-emitting diode 12. The electronic board is arranged in the bottom of the housing 8 so that the light-emitting diode illuminates the front portion 10 of the housing. The front portion 10 is transparent and / or translucent to the light beam emitted by the light-emitting diode 12 in order to display a light signal and / or illuminate a scene. In other words, the light module 2 according to the invention can be a signaling device and / or a lighting device for a motor vehicle.

[0024] As is known, the light module 2 includes an optical reflector 18 arranged between the electronic board 14 and the front part of the housing 4, so as to control the direction of the light beam emitted by the light-emitting diode 12. In this example, the reflector consists of a support covered with a light-reflecting metallic layer. The electronic board 14 and the reflector 18 are held in the rear part 6 of the housing by means of tabs 20 extending from an inner face 22 of the rear part.

[0025] The rear part 6 is held to the front part 10 of the housing by means of fasteners, in this case metal screws 24A and 24B. More specifically, the rear part 6 has passages 26 configured to lock one part of the screws, in this case their heads 28A and 28B, and allow passage of a second part formed by their threaded shanks 30A and 30B. The front portion 10 of the housing includes, on its inner face 32, protrusions 34. Each protrusion forms a cavity opposite a passage 26, designed to receive the threaded shank of a screw 24A or 24B, in order to secure the rear portion 6 to the front portion 10. It should be noted that screw 24A passes through one end 36 of the reflector to ensure better retention of the reflector between the front portion 10 and the rear portion 6 of the light module. Conversely, screw 24B does not pass through the reflector 18 but is located near it.

[0026] The screw heads 26A and 26B are therefore flush with the outside of the light module 2, and the light module is partially traversed by their threaded shanks 30A and 30B. As mentioned above, the screws are made of metallic materials due to their resistance to impacts and temperature variations. However, the metallic nature of the screws has the disadvantage of creating electrically conductive passages, allowing for the formation of electrostatic discharges between the outside and inside of the light module.

[0027] To remedy this problem, the invention proposes inserting a protective element inside the light module 2. More specifically, a protective element according to this example is formed by a protrusion on the rear part 6 of the light module at its inner face 22. Each protrusion forms a sheath 38 encircling a threaded rod of a screw. Naturally, the sheath also surrounds the protrusion 34 into which the screws 24A and 24B are screwed. In other words, each protrusion on the rear part 6 forms a lateral wall 40, 40A, 40B extending along a threaded rod. The lateral wall 40, 40A, 40B preferably completely surrounds the threaded rods of the screws.

[0028] According to this example, the side wall forming the sheaths 38 is made of a plastic material identical to that of the rear part 6 of the light module 2. The rear part 6 of the light module is made from one of the following materials: acrylonitrile butadiene styrene (ABS), polycarbonate (PC), or a mixture of the two. The thickness of the side wall 40, 40A, 40B is chosen to prevent the passage of electrostatic discharges through the sheath 38. Depending on the material forming the sheath, the thickness of the side wall is between 2 mm and 3 mm.

[0029] According to the invention, the side wall of the sheaths 38 extends along a threaded rod such that the shortest path C between the threaded rod and the reflector 18, passing between an appendage 34 and a sheath 38, is equal to or greater than 20 mm. If necessary, the side wall of a sheath can extend beyond the end of a threaded rod. The sheath thus prevents the formation of an electrostatic discharge via the screws 24A and 24B, between the outside of the light module 2 and the reflector 18. As a result, the light reflector is less likely to transmit an electrostatic discharge to the light-emitting diode 10, which could damage it.

[0030] It should be noted that the side wall forming the sheath 38 varies in length around the threaded rod 30B. The term "length" refers to a dimension of the sheath along a direction substantially longitudinal to the threaded rod it surrounds. Indeed, as mentioned above, the sheath's function is to prevent the passage of an electrostatic discharge between the threaded rod and an electrically conductive element present in the light module 2. The side wall 40B of the sheath 38 can therefore be shorter than the side wall 40A when the side wall 40B is not opposite an electrically conductive element. This advantageously reduces the sheath's overall size within the light module to facilitate its integration.

[0031] The embodiment described above may include the following variations.

[0032] According to one variant, the cross-section of a sheath can be oval or pentagonal in shape, preferably circular or square.

[0033] According to a second variant, the length of the sheath around a threaded rod can vary between 200% and 0% of the length of the threaded rod, preferably between 60% and 30%.

[0034] According to a third variant, the length of a sheath can be zero on part of its contour so as to form a more or less curved wall, interposed between an electrically conductive element and a threaded rod.

[0035] According to a fourth variant, the sheath can be formed by an element distinct from the rear part 6 of the light module.

Claims

1. A luminous module (2) for a motor vehicle, said module comprising a casing (4) in which an electrically conductive support (18) and at least one semiconductor light source (12) in contact with or near the support (18) are present, the luminous module (2) also comprising at least one electrically conductive fastening means (24A, 24B) comprising a first portion (28A, 28B) located outside the casing (4) and a second portion (30A, 30B) passing near or through the support (18), the luminous module (2) comprising a protective element (38) against electrostatic discharge, arranged between the second portion (30A, 30B) of the fastening element and the support (18), the protective element (38) extending along the second portion (30A, 30B) of the fastening means (24A, 24B) so as to prevent the passage of an electrostatic discharge between the fastening means (24A, 24B) and the support (18), characterized in that the protective element (38) extends from an inner face (22) of the casing (4).

2. The luminous module (2) according to the preceding claim, characterized in that the protective element (38) is formed from a plastics material of the acrylonitrile butadiene styrene (ABS) or polycarbonate (PC) type or a mixture of the two.

3. The luminous module (2) according to any one of the preceding claims, characterized in that the thickness of the protective element (38) is between 1 mm and 10 mm or between 2 mm and 8 mm, preferably between 2 mm and 3 mm.

4. The luminous module (2) according to any one of the preceding claims, characterized in that the protective element (38) extends along the second portion (30A, 30B) of the fastening means (24A, 24B), so that the shortest path (C) bypassing the protective element (38), between the fastening means (24A, 24B) and the support (18), is equal to or greater than 20 mm.

5. The luminous module (2) according to any one of the preceding claims, characterized in that the protective element (38) is a sheath partially or completely surrounding the second portion (30A, 30B) of the fastening means (24A, 24B).

6. The luminous module (2) according to the preceding claim, characterized in that the length of the sheath varies around the fastening means (24A, 24B).

7. The luminous module (2) according to the preceding claim, characterized in that a side wall (40B) of the protective element (38) is shorter, when said side wall is opposite a non-conductive element.

8. The luminous module (2) according to any one of the preceding claims, characterized in that the protective element (38) is integral with the inner face (22) of the casing (4).

9. The luminous module (2) according to any one of the preceding claims, characterized in that the fastening means (24A, 24B) is reversible.

10. The luminous module (2) according to the preceding claim, characterized in that the fastening means (24A, 24B) is a fastening screw comprising a head (28A, 28B) flush with the outside of the casing (4) and a threaded rod (30A, 30B) extending inside the casing (4).

11. The luminous module (2) according to any one of the preceding claims, characterized in that the support is an electronic card (14) comprising conductive tracks (16) connected to at least one light source (12) or an optical reflector (18) comprising a metallic layer.

12. The luminous module (2) according to any one of the preceding claims, characterized in that the semiconductor light source (12) is a light-emitting diode.

13. A signaling and / or lighting device for a motor vehicle, said device comprising a luminous module (2) according to any one of the preceding claims.

14. A motor vehicle comprising a signaling and / or lighting device according to the preceding claim.